Dental calculus, or tartar as it is sometimes called, is a deposit which forms on the surfaces of the teeth at the gingival margin. Supragingival calculus appears principally in the areas near the orifices of the salivary ducts; e.g., on the lingual surfaces of the lower anterior teeth and on the buccal surfaces of the upper first and second molars, and on the distal surfaces of the posterior molars.
Mature calculus consists of an inorganic portion which is largely calcium phosphate arranged in a hydroxyapatite crystal lattice structure similar to bone, enamel and dentine. An organic portion is also present and consists of desquamated epithelial cells, leukocytes, salivary sediment, food debris and various types of microorganisms.
As the mature calculus develops, it becomes visibly white or yellowish in color unless stained or discolored by some extraneous agent. This is undesirable from an aesthetic standpoint.
A wide variety of chemical and biological agents have been suggested in the art to retard calculus formation or to remove calculus after it is formed. Mechanical removal of this material periodically by the dentist is, for course, routine dental office procedure.
The chemical approach to calculus inhibition generally involves chelation of calcium ion and/or crystal growth inhibition which prevents the calculus from forming and/or breaks down mature calculus by removing calcium.
The prior art discloses a number of chelating agents for this purpose. British Pat. No. 490,384, Feb. 15, 1937, discloses oral compositions containing ethylenediaminetetraacetic acid, nitrilotriacetic acid and related compounds as anticalculus agents. U.S. Pat. No. 3,678,154, July 18, 1972 to Widder et al. discloses oral compositions containing certain polyphosphonates and fluoride. U.S. Pat. No. 3,737,533, June 5, 1973 to Francis discloses oral compositions containing certain carbonyl diphosphonates.
In addition to the above references, the prior art discloses dentifrices and mouthwashes containing soluble pyrophosphate salts which have been included for a variety of purposes. Included among such references are U.S. Pat. No. 2,941,926, June 21, 1960 to Salzmann et al. which discloses dental powders containing chlorophyll and pyrophosphate salts. U.S. Pat. No. 3,137,632, June 16, 1964 to Schiraldi discloses toothpastes containing pyrophosphate salts. U.S. Pat. Nos. 3,927,201 and 3,927,202, Dec. 16, 1975 to Baines et al. and Harvey et al., respectively, disclose toothpastes which utilize soluble pyrophosphates as abrasives. U.S. Pat. Nos. 4,244,931, Jan. 13, 1981 and 4,247,526, Jan. 27, 1981 to Jarvis et al. disclose pyrophosphate salts in dicalcium phosphate systems. Japanese Patent Application Disclosure No. 4945-1974 discloses soluble pyrophosphates in a variety of dentifrice systems. U.S. Pat. No. 4,323,551, Apr. 6, 1982 to Parran discloses tetraalkali metal salts in mouthwash compositions.
In addition to the use of the above mentioned materials the use of certain acrylic acid polymers and other agents have also been disclosed for use as anticalculus agents. Included among such agents are polyelectrolytes such as copolymers of maleic anhydride and ethylene disclosed in U.S. Pat. No. 3,429,963, Feb. 25, 1969 to Shedlovsky. Shedlovsky also discloses polyacrylic acid having an average molecular weight of 1500 and greater. Other references disclosing polyacrylic acids in oral compositions are South African Pat. No. 720898, Sept. 12, 1972 which discloses such acids having a molecular weight of from 1000 to 2,000,000; and U.S. Pat. No. 4,304,766, Dec. 8, 1971 to Chang discloses polyacrylic acid having a molecular weight in the range of 2,000 to 4,000,000 for use as a membrane to prevent the elution from teeth of previously applied agents. Finally, U.S. Pat. No. 3,956,480, May 11, 1976 discloses complexes of anionic polymers (e.g., acrylic acid) and a cationic therapeutic agent (e.g., chlorhexidine) as anticalculus agents.
In addition to the above described materials, strontium edadate has been disclosed in dentifrice compositions for use in controlling calculus. One reference having such a disclosure is U.S. Pat. No. Re. 30,675, July 14, 1981.
In spite of the many disclosures in the anticalculus area, the need for improved anticalculus products still exist. The prior art, while disclosing strontium complexes and pyrophosphate salts as anticalculus agents, does not teach or suggest the combining of such agents to achieve an enhanced benefit.
It is an object of the present invention to provide compositions which deliver an effective anticalculus benefit.
It is a further object of the present invention to provide an effective anticalculus product utilizing polyacrylic acid polymers or copolymers having a mass average molecular weight of from about 3500 to about 7500.
It is a further object of the present invention to provide an anticalculus product which does not inhibit remineralization of the teeth.
It is still a further object of the present invention to provide an effective method for treating calculus.
It is still a further object of the present invention to provide compositions which are cosmetically acceptable.
These and other objects will become more clear from the detailed description which follows.
All percentages and ratios used herein are by weight unless otherwise specified. Also all measurements referred to herein are made at 25.degree. C. in the composition unless otherwise specified.